- Depending upon your rig and tire size. At what point do you think components directly effected because of the larger tire size would need to be replaced?
- Would you replace these first?
- Re-Gearing?
- Ball Joints?
- Axle Trusses and C-Gussets?
- Axle Shaft Upgrades?
- Bigger brakes to compensate for the larger tires?
- Power Steering Upgrades?
- Drive Shaft Upgrades?
- Or would you do these later?
Just a little tidbit for those of you deciding to do with a larger tire size, and are considering re-gearing based on the size of tire. You should know that going to a much larger tire than the stock tires will cause the engine/transmission to not shift within the correct RPM range. This can somewhat affect your gas mileage and power outputs(torque).
So here is a simple math equation to figure out what differential gearing you will need when you upgrade to a larger tire size. Now understand that companies who manufacture differential gears do not make gears in a crazy amount of ratios. So try to get the differential gearing closest to the number you come up with.
So here is the formula!
NEW TIRE SIZE x OLD RATIO = NEW RATIO
OLD TIRE SIZE
To help make sense of this equation we will use a stock 2011 JKU (Jeep Wrangler Unlimited non-Rubicon) with a DANA 30 (Front Axle) and a DANA 44 (Rear Axle) as an example.
The Jeep comes stock with 225/75R17 tires, this tire size in inches equals 32.1. Also depending upon the model it will have either a 3.12 or a 3.73 differential gear ratio.
We will use the 3.73 gearing in this equation.
So you decide to upgrade to 35 inch tires, below is the formula calculated for you.
35" x 3.73 ratio = 130.55/32.1" = 4.06 ratio
So here is a simple math equation to figure out what differential gearing you will need when you upgrade to a larger tire size. Now understand that companies who manufacture differential gears do not make gears in a crazy amount of ratios. So try to get the differential gearing closest to the number you come up with.
So here is the formula!
NEW TIRE SIZE x OLD RATIO = NEW RATIO
OLD TIRE SIZE
To help make sense of this equation we will use a stock 2011 JKU (Jeep Wrangler Unlimited non-Rubicon) with a DANA 30 (Front Axle) and a DANA 44 (Rear Axle) as an example.
The Jeep comes stock with 225/75R17 tires, this tire size in inches equals 32.1. Also depending upon the model it will have either a 3.12 or a 3.73 differential gear ratio.
We will use the 3.73 gearing in this equation.
So you decide to upgrade to 35 inch tires, below is the formula calculated for you.
35" x 3.73 ratio = 130.55/32.1" = 4.06 ratio
So a 4.06 gear ratio would be the new ratio required to keep your RPM shifts within the range the engine/transmission were designed to shift. This will also help provide more torque to handle the larger tires, better performance when towing/carrying a lot of weight, and off-roading.
Since pretty much no one to my knowledge (correct me if I'm wrong) makes a 4.06 differential gearing for a 2011 Jeep Wrangler Unlimited. The closest one available that you will find is a 4.11 ratio, that will more than get the job done if gas mileage/more torque is what you care about.
Since pretty much no one to my knowledge (correct me if I'm wrong) makes a 4.06 differential gearing for a 2011 Jeep Wrangler Unlimited. The closest one available that you will find is a 4.11 ratio, that will more than get the job done if gas mileage/more torque is what you care about.
